The present invention relates to piano regulation and, more particularly, to an apparatus that allows grand piano actions to be assembled and regulated on a benchtop and then fit back into their grand pianos exactly as expected.
When piano technicians, manufacturers, or rebuilders wish to try out parts for a grand piano action, assemble an action, take apart and reassemble an action, or regulate an action, it is useful, but awkward and difficult, to accurately record, store and display the scale of a grand piano, including both hammer spacing and string heights for all sections at once.
Grand piano actions are particularly difficult to work on and have this work done correctly. This is partly because the actions live under the piano's pinblock, where lighting is bad, access is extremely limited, and adequate sightlines are not available. The technician often depends on symptoms, educated guesses and trial-and-error work-arounds to execute the subtleties of work on grand piano actions.
Although good hammer-to-string fit is the foundation for good tone (and bad hammer-to-string fit undermines it), technicians are often faced with unsatisfactory compromises in order to achieve it. Distorting string level, misshaping hammers, and adjusting travel or squareness of hammers without really knowing where the ideal should be are frustrating choices to the earnest technician. At the end of the job, inconsistent outcomes can generate the need for voicing measures that won't work as well as hoped because they don't correct the underlying inaccuracy.
Another hard-to-control aspect of grand action work is what happens after strike. Properly adjusting verticality, particularly in hammer travel and strike, maximizes stability in the bounce. Parts that travel straight up and bounce straight back improve both repetition and power. Repeated notes are easier to control if the hammers aren't bounced out of alignment. The stress and friction in centers pulling hammers back into alignment drain power and increase wear, and the inconsistency of hammers in varying degrees of compliance erodes control and undermines voicing.
As can be seen, there is a need for an apparatus that allows grand piano actions to be assembled and regulated on a benchtop and then fit back into their pianos exactly as expected. Traditional methods have depended on important references that are imprecise and, in particular, fail to match the effective surface of the benchtop to the surface of the piano's keybed.